The company took a modest amount from every transaction

"The problem is, obviously, that it legitimized too much trading. It made it too easy D2R ladder items. I'm sure that we've all heard about this now, and the consequences. We were worried about the ramifications in the past We believed that the benefits would outweigh the negatives. World of Warcraft's auction house] seemed to be a great example of this. We clearly were not. "

The issue was rooted in two key areas. The first is that the auction house featured a real-money component, which allowed players purchase loot straight. This allowed Blizzard to criticism over its engineering of low-quality loot drops in order to increase the market value. 

The company took a modest amount from every transaction, it took a small cut from every. Whether or not this was the case, the overall quality of loot was extremely poor at launch, and fans were justifiably suspicious--especially given that Blizzard's acquisition from Activision was only a few years old at this point, and longtime Blizzard fans were watchful for any resulting changes in corporate culture. 

In addition, the existence of an actual-money market made anti-cheat strategies which are more crucial for the safety of the game. If one could make the value of a product indefinitely, for instance, it could result in scams and eventually decrease the value of the items. 

This was a part of the"always-online" feature that caused players to be frustrated in the early days. If you're always online the system constantly checks for glitches such as duplication and other glitches, but it didn't make players who chose to only play offline feel any better. 

What Blizzard was dealing with was one feature that fans didn't like buy d2r items, that existed mostly to support the technical underpinnings of another feature that fans weren't happy with.